robertson



May 30, 1 33- J. R. ROBERTSON 11,911,584

SCREEN FOR COLOR PHOTOGRAPHY Filed- Jan. 11, 1928 2 Sheets-Sheet 1 Tan You" Rosanne". lnverrroR.

mammy 30, 1933- J. R. FIQOBERTSON 1,911,584

SCREEN FOR COLOR PHOTOGRAPHY Filed Jan. 11, 1928 2 Sheets-Sheet 2 A V I K I \\l l/ w if; R2 O I R INVENTOR'. Times ROBERT ROBERTSON.

'PER. 1

ATTORNEY.

Patented May 30, 1933 PATENT; OFFICE JAMES ROBERT nonnn'rson, or LONDON, ENGLAND SCREEN FOB COLOR PHOTOGRAPHY Application filed January 11, 1928, Serial Raj-18,055, andin Great Britain January 22, 1827.

This invention relates to improvements in and relating to screens for ,color photography and-in particular to the projection of movin pictures in colors.

According to the present invention a number of color screens are provided between the projecting apparatus and the viewing screen, and each color screen comprises a vacuum chamber containing a different gas,

adapted to assumefor example a red, green and blue color respectively when an electron discharge is passed through the gas in the vacuum chamber. The electrodes in each chamber are in circuit with circuit closing 16 and opening means operable from the projecting apparatus, the electrodes of the several chambers being put in circuit in turn so that first, say, a screen of a red color is formed, next a screen of bluecolor, and so 0 on. The vacuum chambers may also contain mixtures of gases which will assume various desired colors when an electron discharge is passed.

One or more of the vacuum chambers may be surroundedby an annular vacuum chamber also containing a gas or a mixture of gases and also adapted to assume a color when an electron discharge is passed therethrough, and the electrodes of these annular chambers are likewise connected with circuit making. and breaking devices controlled by the projecting device. The color assumed by the gas in the annular chamber has a modifying effect upon the. color assumed by the chamber within the annular chamber.

The color screens are preferably mounted in a tubular member and the tubular member may also carry one or more optical lenses.

In addition to having a screen of the above type varying in color as desired, the source of light used for projection may comprise a group of vacuum tubes containing different gases so that the color of said source of light may be varied in accordance with that of the screen.

In the accompanying drawings,

Fig. 1 illustrates diagrammatically in sectionalelevation one form of construction of the color screen according to the present in-v vention.

Fig. 2 illustrates diagrammatically a moving picture projection system in accordance with the invention.

Fig. 3 illustrates in front elevation switching means for the vacuum chambers of the invention which are operable by the film driving mechanism. j

Fig.4 is a sectional elevation on line 4--4 of F 1 3.

In Fig. 1, E is a tube of metal within which are mounted three vacuum chambers C, C, C in alignment. In the construction illustrated the three chambers are of cylindrical form. Surrounding each chamber C, C, C are arranged annular vacuum chambers F, F F All the vacuum chambers contain a gas or a mixture of gases, the chamber C containing for example neon, which on the passingof an electron discharge therethrough will become red in 001-. or, J may be a chamber of uranium glass or ordinary glass coated with Willimite and containing G0,, which will produce a fluorescent green color, and C containing argon, which will give a blue color. The annular chambers F, F F also contain gases adapted, on the passing of a discharge, to assume a color which will modify gy its pro inquity the color in the chamber C or For example the annular chamber F may contain hydrogen or another gas which assumes an orange hue, so that the red of the gas in chamber C becomes tin ed. with orange.

In each chamber C, 5, C are electrodes G, G, G, and in each annular chamber F, F F are electrodes H, H H and these electrodes are all in circuit with a current supply and the circuits to each'pair ofelectrodes is made or broken by mercury.

switches D, D, D. These switches are op low in connection with Figs. 3 and 4. Thus switch D is closed and vacfor one picture,

is converted into a red uum chamber screen by the discharge passed therethrough;

- red light,

for the next picture switch D is opened and switch D closed," converting chamber G into a green screen; and so on. The switches D, D, D may operate simultaneously'the vacuum chambers C, C, C andthe annular chambers surrounding them, or if the chambers C, C, C only are being used the switches D, D D may be single switches.

Combined with thechambers C, C C, may be used any suitable optical lenses A, B, which may be apo-chromatic lenses sealed to the ends of the chambers for directing the light rays coming through the through the color screens on to the viewing screen.

In Fig. 2, the source of light for projecting the pictures on the screen may be a group of vacuum tubes J containing difierent gases, in circuit withmercury switches N, N, N, so as to throw beams of colored light in turn on a discharge passing through the tubes light condensers K, on to and through the film L and thence through a shutter O and a device M similarfto thescreen device described above in connection with Fig. 1.

when a film has a picture opposite the shutter opening, vof an object which has been hotographed for example through a red creen or has been photographed when flooded with red-"light. The switch N puts incircuit one ofthe series of tubes J producing and simultaneously a gaseous screen in the device M which only permits red light to pass. object are thus shown on the screen. On the next picture being presented before the .shu'tte'r openin the switch N is opened and the switch 1 puts in circuit other tubes J giving, say, a green light, and simultaneously the green gaseous color screen in device M is excited and so on.

Instead of the vacuum tube device J asource of white light may be employed which is not affected b the switches N, N. Again a-source 0 white light may be used in combination with the vacuum color tubes.

The .switches N, N, N the film advancing sprocket T,

are operated by which is driven through intermittent gearing in known manner by a motor. The operation of the switches is illustrated in greater de tail in Figs. 3 and 4. The switches N, N, N are pivotally mounted at their rear ends on a shaft P and are adapted to be moved 'rality of gas aided by the reflector I, through- The red elements in the switch to flow into the front end thereof I and make contact between two wires X (or X or X as the case may be) and thus switch in one of the vacuum chambers. In the position illustrated in Fi ures 3 and 4, switch N is shown in the tfiosed position and switches N and N are shown in the open position.

What I claim is: y

1. color screen device for use in connect1on with movin pictures comprising a plucharge chambers aligned and each adapted to assume a different color upon electrical excitation and means for exciting said chambers in turn.

2. A color screen device for use in connection with moving pictures'comprising a plurality of gas dischar e chambers each adapted to assume a dierent color upon excitation, a gas discharge chamber of sub-. stantially annular form surrounding at least one of said first named chambers and adapted to assume a color u :1 electrical excitation, and means whereby all of said chambers can be excited in turn.

3. In a motion picture projector for projecting pictures in color, a .p uralit of gas discharge chambers aligned and eac adapted to assume a difierent color upon electrical excitation, electrodes mounted 1n said chambers means whereby an electric potential can be applied to said electrodes .in turn, an optical lens in alignment with said chambers, and a sleeve wherein said chambers and optical lens are mounted.

4. In a motion picture projector for projecting pictures in color, a plurality of gas discharge chambers aligned and each adapted to assume a different color upon electrical excitation, a gas discharge chamber of substantially annular form surrounding at least one of said first named chambers and adapted to assume a color u on electrical excitation, electrodes mounts in all of said chambers, means whereby an electric potential can be applied to said electrodes in turn an optical lens in ali cut with said first named chambers an a sleeve wherein all of said chambers and said optical lens are mounted.

5. A moving picture projection system for projecting pictures in color comprising a projection light source, a li ht condenser, a picture film, means for a vancing said film, an optical lens, a color screen comprising a plurality of gas dischar e chambers each adapted to assume a di erent color upon electrical excitation and switches, op-

erable by said means for advancing the pic-- ture film adapted to control the excitation of said chambers. 6. A moving pictureprojection system according to claim '5, wherein said projection light source comprises a plurality of gas discharge tubes each adapted to assume a different color upon electrical excitation and 'adapted' to be excited in synchronism with the gas discharge "chambers of the color screen.

In'testimony whereof I have signed my name to this specification. 

